@@ -168,11 +168,15 @@
 		if ([mode isEqual: @"r"]) {
 			_mode = OF_ZIP_ARCHIVE_MODE_READ;
 
 			[self of_readZIPInfo];
 			[self of_readEntries];
-		} else
+		} else if ([mode isEqual: @"w"] || [mode isEqual: @"a"])
+			@throw [OFNotImplementedException
+			    exceptionWithSelector: _cmd
+					   object: self];
+		else
 			@throw [OFInvalidArgumentException exception];
 	} @catch (id e) {
 		[self release];
 		@throw e;
 	}